cranial nerve examination

What are the key components assessed in a mental status examination?

Appearance/behavior, sensorium/cognition, mood/affect, speech, thought process, thought content, perceptual disturbances, insight/judgment. Mental Status 1

What does the mental status examination focus on in emergency settings?

Assessment of orientation and level of consciousness using standardized scales (e.g., Glasgow Coma Scale). Mental Status 2

Types of Aphasia

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Back Subtopic Number

What is aphasia?

The inability to either form or understand language, not attributed to the motor ability to produce speech. Caused by damage to dominant hemisphere language areas. Aphasia 3

What are the clinical features of Broca aphasia (motor/expressive)?

Nonfluent, telegraphic, grammatically incorrect speech; comprehension largely spared (may struggle with complex); patient aware/frustrated; impaired repetition. Aphasia 4

Where is the typical lesion location for Broca aphasia?

Broca area (inferior frontal gyrus). Aphasia 5

What are the clinical features of Wernicke aphasia (sensory/receptive)?

Fluent speech lacking sense (paraphasic errors, neologisms, word salad); impaired comprehension; patient typically unaware; impaired repetition; reading/writing impaired. Aphasia 6

Where is the typical lesion location for Wernicke aphasia?

Wernicke area (superior temporal gyrus). Aphasia 7

What are the clinical features of Global aphasia?

Nonfluent; severe impairment of speech production and comprehension; patient may be mute or utter sounds; unable to comprehend speech. Aphasia 8

What lesion locations cause Global aphasia?

Broca area, Wernicke area, and arcuate fasciculus. Aphasia 9

What are the clinical features of Conduction aphasia (associative)?

Fluent speech and mostly intact comprehension; impaired repetition with paraphasia (patient tries to correct mistakes). Aphasia 10

What is the typical lesion location for Conduction aphasia?

Arcuate fasciculus of the parietal lobe. Aphasia 11

What are the clinical features of Anomic aphasia?

Fluent speech with isolated difficulty finding words; paraphrasing occurs when word is not found. Aphasia 12

Is lesion localization typically possible for Anomic aphasia?

No, usually pinpointing the localization of the lesion is not possible. Aphasia 13

What are the clinical features of Transcortical motor aphasia?

Nonfluent; difficulty initiating speech, expressing thought, producing own phrases; intact repetition and comprehension. Aphasia 14

What is the typical lesion location for Transcortical motor aphasia?

Supplementary motor area (frontal lobe), with Broca area intact (or during Broca recovery). Aphasia 15

What are the clinical features of Transcortical sensory aphasia?

Fluent; impaired speech expression and comprehension; errors in paraphrasing; poor comprehension; intact repetition. Aphasia 16

What is the typical lesion location for Transcortical sensory aphasia?

Various areas of the temporal lobe, with Wernicke area intact. Aphasia 17

What are the clinical features of Transcortical mixed aphasia?

Nonfluent; poor comprehension of spoken and written language. (Repetition is often preserved if surrounding areas affected but key areas intact). Aphasia 18

What is the typical lesion location for Transcortical mixed aphasia?

Broca area, Wernicke area, and arcuate fasciculus are intact, but surrounding watershed areas are affected. Aphasia 19

Cranial Nerve Examination (Overview Table & Detailed Text)

CN I: Olfactory Nerve

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Back Subtopic Number

What is examined for Cranial Nerve I (Olfactory)?

Olfaction (sense of smell). CN I Exam (Overview) 20

How is CN I (Olfaction) tested?

Patient blocks one nostril, closes eyes, sniffs repetitively. Present nonirritating substance (vanilla, coffee), ask to detect and identify odor. Repeat for other nostril. CN I Exam (Overview) 21

What sense does Cranial Nerve I (Olfactory) convey?

Sense of smell. CN I Detail 22

What are potential abnormalities/symptoms of Cranial Nerve I (Olfactory) damage?

Anosmia (loss of smell) or parosmia (distorted smell). CN I Detail 23

Is bedside testing of smell (CN I) generally considered of high clinical value?

No, bedside testing of smell is of limited clinical value and rarely performed. CN I Detail 24

What is an example of an objective smell test for CN I?

'Scratch and sniff' test cards, such as the University of Pennsylvania Smell Identification Test (UPSIT). CN I Detail 25

What is hyposmia?

Reduction of the sense of smell. CN I Detail 26

What is anosmia?

Loss of the sense of smell. CN I Detail 27

List three causes of hyposmia or anosmia related to CN I.

Upper respiratory infection, sinus disease, head injury (olfactory filament damage), olfactory groove meningioma, basal skull tumors. CN I Detail 28

In which two neurodegenerative diseases may disturbance of smell (CN I) occur very early?

Parkinson's disease and Alzheimer's disease. CN I Detail 29

What taste disturbance often accompanies anosmia (CN I dysfunction)?

Hypogeusia (reduced taste) or ageusia (loss of taste), as taste is crucially influenced by the sense of smell. CN I Detail 30

What is parosmia, a potential CN I abnormality?

The perception of pleasant odors as unpleasant. CN I Detail 31

What can cause parosmia (CN I)?

Head trauma, sinus infection, or an adverse effect of drugs. CN I Detail 32

In what conditions might olfactory hallucinations (CN I related) occur?

Alzheimer's disease and focal epilepsies. CN I Detail 33

CN II: Optic Nerve

Front

Back Subtopic Number

What aspects are examined for Cranial Nerve II (Optic)?

Visual acuity, color vision, visual field, papilla (optic disc via fundoscopy), pupillary light reflex, pupil shape and width. CN II Exam (Overview) 34

How is visual acuity (CN II) tested?

Patient reads from a Snellen chart (one eye at a time), correcting for refractive errors with glasses or pinhole. CN II Exam (Overview) 35

How is color vision (CN II) tested?

Patient identifies numbers/shapes within Ishihara plates (dots of different color/size) with both eyes. CN II Exam (Overview) 36

How is the visual field (CN II) assessed by confrontation?

Compare patient's visual fields to examiner's using a finger or red pin. Test all 4 quadrants by bringing finger/pin from periphery towards center. CN II Exam (Overview) 37

What is examined during fundoscopy for CN II assessment?

Optic disc (papilla): color, size, swelling, elevation. Retina: color, texture, retinal vessels (size, hemorrhages, exudates). CN II Exam (Overview) 38

How is the pupillary light reflex (CN II afferent, CN III efferent) tested?

Examiner shines light into patient's eye. Normal: prompt, consensual (equal in both eyes) pupillary constriction. CN II Exam (Overview) 39

What is observed about pupil shape and width (CN II/III)?

Healthy pupils are isocoric (equal size) and 2-8 mm. Anisocoric or abnormal size suggests a disorder. CN II Exam (Overview) 40

What is mandatory to assess in all ophthalmic patients regarding CN II?

Assessment of visual acuity. CN II Detail 41

If a patient cannot see the largest font on a Snellen chart at 6m, what are the next steps?

Reduce test distance to 3m, then 1m. If still unable, document if can count fingers, see hand movement, or perceive light/dark. CN II Detail 42

How is visual acuity expressed using a Snellen chart?

Distance text is read (e.g., 6m) / number of smallest font line read correctly (e.g., 6/60 = sees at 6m what normal sees at 60m). CN II Detail 43

What is the purpose of using a pinhole if a patient cannot read down to line 6/6 (CN II)?

To correct any residual refractive error. CN II Detail 44

What is considered normal vision on a Snellen chart (CN II)?

6/6. CN II Detail 45

What is the normal extent of the visual field horizontally and vertically (CN II)?

160 degrees horizontally and 130 degrees vertically. CN II Detail 46

Where is the physiological blind spot located in the visual field (CN II)?

15 degrees temporal to the point of visual fixation, representing the optic nerve head entry. CN II Detail 47

How can more subtle visual field defects be elicited using a hatpin or Neurotip (CN II)?

Bring a small white target from periphery to center; patient says when they first see it. Test all 4 quadrants separately for each eye. CN II Detail 48

How is the blind spot tested using a red-tipped target (CN II)?

Place target at fixation, move temporally until it disappears, then move slowly up/down/side-to-side until it reappears, comparing to examiner's blind spot. CN II Detail 49

What are potential abnormalities/symptoms of Cranial Nerve II (Optic) damage?

Partial sight/blindness, scotoma, hemianopia, anisocoria, impaired/lost pupil reflex, optic disc/retinal changes. CN II Detail 50

What does it indicate if visual acuity (CN II) is not improved with a pinhole?

Indicates eye disease not related to the refractive apparatus alone, such as retinal or optic nerve pathology. CN II Detail 51

What does a dull or pale red appearance of a red target suggest during visual field testing (CN II)?

Suggests colour desaturation, which may indicate optic nerve dysfunction. CN II Detail 52

CN III, IV, VI: Oculomotor, Trochlear, Abducens Nerves

Front

Back Subtopic Number

What is examined for Cranial Nerves III, IV, and VI?

Eye movement (saccades, smooth pursuit), visual accommodation, eyelid ptosis. CN III,IV,VI Exam (Over.) 53

How are saccades (CN III, IV, VI) evaluated?

Patient looks back and forth between two widely spaced targets (e.g., examiner's fingers) held in front. CN III,IV,VI Exam (Over.) 54

How are smooth pursuit eye movements (CN III, IV, VI) tested?

Patient follows a finger moving up, down, laterally, and diagonally. Observe for paresis, alterations (saccades), nystagmus. CN III,IV,VI Exam (Over.) 55

How is visual accommodation (CN III) tested?

Physician moves a finger towards the patient. Normal response is pupil constriction. CN III,IV,VI Exam (Over.) 56

How is eyelid ptosis (CN III - Levator palpebrae superioris) assessed?

Patient is asked to open and close their eyes; observe for drooping of the upper eyelid. CN III,IV,VI Exam (Over.) 57

What general observations are made for CN III, IV, VI?

Carefully examine posture, head position, facial asymmetry, eyelid position, periocular skin, position/symmetry of gaze (squint/strabismus). CN III,IV,VI Detail 58

What is a squint (strabismus)?

Any misalignment of the eyes. CN III,IV,VI Detail 59

What is a manifest squint (tropia)?

A squint present with both eyes open. CN III,IV,VI Detail 60

What is a latent squint (phoria)?

A squint revealed only by covering one eye. CN III,IV,VI Detail 61

What is a concomitant squint?

The angle of squint remains the same in all positions of gaze. CN III,IV,VI Detail 62

What is an incomitant squint, and what does it commonly result from?

The angle of squint deviation is greatest in a single position of gaze; commonly results from paralysis of particular extraocular muscles. CN III,IV,VI Detail 63

What abnormal head postures might be observed with CN IV or CN VI palsy?

Head tilts (seen in CN IV palsy) or head turns (seen in CN VI palsy). These may be subtle. CN III,IV,VI Detail 64

How is the corneal light reflex used to assess for squint (CN III, IV, VI)?

Shine pen torch at patient's eyes; observe reflection on cornea relative to pupil. Reflections should be symmetrical. Asymmetry suggests deviation. CN III,IV,VI Detail 65

What does it suggest if the corneal light reflex is on the nasal aspect of the pupil in one eye?

Suggests the eye is deviated outwards (exotropia). CN III,IV,VI Detail 66

Describe the cover/uncover test to confirm a manifest squint (tropia).

Patient looks at pen torch, cover one eye. Observe uncovered eye for movement. Inward movement = exotropia. Outward movement = esotropia. Repeat for other eye. CN III,IV,VI Detail 67

How is the alternating cover test performed to elicit a latent squint (phoria)?

Cover eyes alternately and quickly while patient fixates on pen torch (cover ~2s, move <1s). Movement repeated multiple times. CN III,IV,VI Detail 68

If diplopia is present during ocular movement testing, what should be determined?

Whether it is horizontal, vertical, or a combination, and where the image separation is most pronounced. CN III,IV,VI Detail 69

What is the oculocephalic (doll's-eye) reflex?

The ability of the eyes to remain fixated while the head is turned in the horizontal plane. CN III,IV,VI Detail 70

What are potential abnormalities/symptoms of damage to Cranial Nerves III, IV, and VI?

Strabismus, diplopia, nystagmus. CN III,IV,VI Detail 71

What might failure of an eye to move during the cover/uncover test indicate?

May indicate very poor vision in that eye (cannot take up fixation) or that it is restricted from moving. CN III,IV,VI Detail 72

What does an impaired oculocephalic (doll's-eye) reflex indicate?

Indicates a brainstem abnormality. CN III,IV,VI Detail 73

What neurogenic cause of ptosis involves CN III palsy?

Cranial nerve III palsy (distinguished by dilated pupil, affected eye movements). CN III,IV,VI Detail 74

What pupil abnormality can be caused by a CN III palsy?

A dilated pupil. CN III,IV,VI Detail 75

Pupils (Related to CN II - Afferent, CN III - Efferent)

What is physiological anisocoria, and in what percentage of the population is it seen?

Unequal pupil size, seen in 20% of the population. Pupils Detail 76

How is it determined which pupil is abnormal in anisocoria?

Increase/decrease illumination. If anisocoria is greater in bright light, larger pupil is abnormal. If greater in dim light, smaller pupil is abnormal. Equal degree = physiological. Pupils Detail 77

How is the direct light reflex tested?

With patient fixating distantly, shine bright light from temporal side into one eye, look for ipsilateral pupil constriction. Pupils Detail 78

How is the consensual light reflex tested?

Assess pupil response in the contralateral pupil when light is directed towards the ipsilateral pupil. Pupils Detail 79

What is a Relative Afferent Pupillary Defect (RAPD)?

Occurs when disease of retina or optic nerve reduces the eye's response to light. Tested by swinging flashlight test. Pupils Detail 80

How is a Relative Afferent Pupillary Defect (RAPD) detected using the swinging flashlight test?

Move light briskly between eyes (min 3s each). In RAPD, light in affected eye causes weaker constriction (apparent dilatation) compared to light in normal eye. Pupils Detail 81

How is pupil accommodation tested?

Ask patient to look at a close fixation target (not a light) after fixating on a distant target. Pupil should constrict on near gaze. Pupils Detail 82

What is light-near dissociation of the pupils?

Failure of pupils to constrict to light, but constriction occurs on near gaze (accommodation). Pupils Detail 83

What are the classic features of Horner's syndrome?

Constricted pupil (miosis due to loss of sympathetic dilator tone) and partial ptosis (denervation of Müller's muscle). May also have anhydrosis. Pupils Detail 84

How can Horner's syndrome diagnosis be confirmed pharmacologically?

Cocaine eye drops will cause pupil dilatation in the unaffected pupil but no dilatation on the affected (Horner's) side. Pupils Detail 85

List three causes of Horner's syndrome.

Demyelination, neck trauma/surgery, apical lung tumour (Pancoast tumour), or carotid artery dissection. (Any 3) Pupils Detail 86

What characterizes Adie's (tonic) pupil?

A mid-dilated pupil that responds poorly to both light and accommodation. May become constricted over time. Thought due to parasympathetic dysfunction. Pupils Detail 87

What is Holmes-Adie syndrome?

Adie's pupil associated with diminished Achilles tendon reflexes. Pupils Detail 88

What characterizes an Argyll Robertson pupil?

The pupil is small and irregular, and reacts to accommodation but not to light (light-near dissociation). Classically due to neurosyphilis. Pupils Detail 89

List two causes of a dilated pupil besides CN III palsy or pharmacological agents.

Physiological anisocoria, post-surgical changes, or Adie's tonic pupil. Pupils Detail 90